Identification of new chromosomes of Saccharomyces bayanus using gene probes from S. cerevisiae

The Saccharomyces cerevisiae genes HIS3 (chr. XV), LYS2 (chr. II), ARG4 (chr. VIII), MF alpha 1 (chr. XVI) and MEL1 (chr. II) and the S. pastorianus gene MELx were used for identification of the homeologous chromosomes in S. bayanus by using pulsed-field gel electrophoresis and Southern blot hybridization. The results showed differences in hybridization intensities and mobilities between the homeologous chromosomes of the two sibling yeasts S. cerevisiae and S. bayanus. The probes HIS3, LYS2, MEL1, and MF alpha 1 identified four new homeologous chromosomes of S. bayanus. The ARG4 probe confirmed the previously identified location of chr. VIII (NAUMOV et al. 1992b). Using the MF alpha 1 gene, another chromosome besides chr. XVI was identified in some S. bayanus strains, suggesting translocation of this sequence to the S. bayanus chromosome that normally migrates to the position of chr. XI of S. cerevisiae.